1. Field of the Invention
The present invention relates to a ratchet device for an electrical component that may be adjusted by rotation, in particular a rotary switch or rotary potentiometer, having a leaf spring that contacts a ratchet contour under spring force.
2. Description of the Background Art
Examples of electrical components that may be adjusted by rotation include rotary switches or rotary potentiometers, such components being used where frequent adjustment of the operating states or preset values is intended. In such circumstances, a ratchet device makes it easy for an operator to locate operating states, which the ratchet device makes perceptible by tactile and sometimes also audible means during the rotary motion. Particularly in the case of resistors that can be adjusted by rotation, the adjustment is made perceptible by a ratchet device. The ratchet means of a ratchet device typically includes a spring element, which generally has a curved projection called a detent projection, and a ratchet disk having one or more adjacent ratchet indentations that has a ratchet contour which cooperates with the detent projection. One of the two ratchet means, either the detent projection or the ratchet contour, is rotationally fixed to an actuator of the relevant component. The other ratchet means, in contrast, is held stationary on the component. The two ratchet means slide relative to one another during the rotary motion, and in the process the ratchet means produce tactile ratchet indications.
Known from German utility model 295 01 692 is a ratchet device consisting of an outer housing and an inner rotor, which rotor is connected to a rotationally adjustable operating element, and a leaf spring arranged in the interior of the rotor. At one point on the rotor, a detent projection of the leaf spring projects out of the cylindrical rotor wall into a ratchet contour located on the inner circumferential surface of the outer housing. During rotary motion, the detent projection initially twists and is pushed back by the rotor wall. When the detent projection snaps into a recess of the ratchet contour, the leaf spring immediately relaxes and strikes the side wall. This impact is audible.
Another arrangement of this generic type of a ratchet device in a component, which may be adjusted by rotation is disclosed in DE 195 05 737. In order to facilitate the defined setting of an angle of rotation, two flat springs are clamped on the inside floor of the housing base. These springs have convexities to interact with a ratchet disk. On its periphery the ratchet disk has, associated with each spring, two corresponding ratchet notches for the adjustable angle of rotation. In addition, the ratchet disk has on its peripheral surface a ramp for each flat spring; when the switch cam is rotated counterclockwise, these ramps provide a return torque to automatically return the switch cam to its base position. In addition, two stops are provided on the ratchet disk which interact with a projection formed on the inside floor of the housing base to limit the rotation of the switch cam.